【作者】 李林坤； 马建； 王苏豪； 昝元峰； 李朋洲；

【Author】 LI Linkun;MA Jian;WANG Suhao;ZAN Yuanfeng;LI Pengzhou;Nuclear Power Institute of China;

【机构】 中国核动力研究设计院；

【摘要】 采用低熔点的金属铅(Pb)、锌(Zn)、锡(Sn)和合金铅锡(Pb-Sn)、铅铋(Pb-Bi)作为模拟材料,通过改变熔化温度、冷却剂温度和入水速度等参数开展熔融物射流破碎实验,获得不同因素影响下的熔融物射流破碎现象学特征;根据整体和局部加速破碎的相关理论分析,揭示不同因素影响下的熔融物射流破碎不稳定机理;进一步通过实验数据与相关熔融物射流破碎模型的对比验证,确定适用于实验条件下的机理模型。研究结果表明,熔融物的熔点越低,膜态沸腾越不稳定,因汽膜坍塌导致其碎化程度越高;熔融物温度与冷却剂之间的温差反映了热力学作用对碎化过程的影响,其机理主要源自于整体加速破碎中的Rayleigh-Taylor不稳定性和局部加速破碎中的Marangoni效应;熔融物入水速度反映了水力学作用对碎化过程的影响,其机理主要包括整体加速破碎中的Kelvin-Helmholz不稳定性和剪切力相关韦伯数,但对碎化过程的影响不明显;在实验条件下,侧重于熔融物热力学碎化机理的Meignen模型更适用于粗混合阶段熔融物破碎速率的预测。更多还原

【Abstract】 Low melting point metalsand alloys lead(Pb), zinc(Zn), tin(Sn), lead-tin(Pb-Sn) and lead-bismuth(Pb-Bi) being used as simulated materials, the melt jet flow broken experiments are carried out by changing the melting temperature, coolant temperature and jet velocity, and the phenomenological characteristics under the influence of different factors are obtained. On the base of the theoretical analysis of acceleration fragmentation regime, the mechanism of instability of melt jet flow broken under the influence of different factors is revealed. Furthermore, the mechanism model suitable for the experimental condition is determined by comparing the experimental data with models. The results show that the lower is the melting point, the more is unstable the film boiling, and the higher is the fragmentation degree due to the collapse of the vapor film.The temperature difference between the melt and the coolant reflects the effect of thermodynamics during the fragmentation process, the mechanism is mainly due to the Rayleigh-Taylor instability and Marangoni effect.The melt jet velocity reflects hydriaulic influence during the fragmentation process, and its mechanism mainly includes Kelvin-Helmholz instability and shear force related Weber number, but this effect on the process of fragmentation is not obvious. Under the experimental condition, Meignen model is more suitable for the prediction of the fragmentation rate of the melt in the coarse mixing stage.更多还原